Firth Rixson Ltd manufactures 1,500 tonnes a year of rings, forgings and special metals for a wide range of engineering usages. At the company’s factory in Glossop, Cheshire it produces a range of cast and wrought nickel, cobalt and iron-based super alloys for prestigious industries such as aerospace, gas turbines, prosthetic surgery, diesel engines and for chemical and nuclear engineering. It has plants in the USA and China as well as the UK.
ABB Drives Alliance partner, Halcyon Drives, was asked to conduct an energy survey at the Glossop factory. Firth Rixson had recently relocated a number of grinding stations, concentrating them in one area, with centralised dust extraction in the fettling and de-scaling plant. The dust extraction is provided by a 75 kW extraction fan motor, run constantly, direct-on-line. Not all of the machines were running simultaneously, meaning that there is often more dust extraction capacity than needed. This was obviously wasteful of energy.
Halcyon Drives suggested introducing an ABB industrial drive to power the 75 kW extraction fan motor. By reducing the speed of the fan, savings of 20% on consumed energy were achieved, saving 44 tonnes of CO2 per annum.
One of the characteristics of this installation is that there are two motors, one a standby. Halcyon Drives had to ensure that the standby was available at all times. The savings at this stage did not justify a standby inverter. Halcyon Drives developed dual standby options in this system by having a change over mechanism so either motor could be driven by the inverter or in the event of a service problem with the inverter; either motor could be started using the existing star/delta starter until the inverter could be re-instated into the system.
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